• Title/Summary/Keyword: HAPs

Search Result 140, Processing Time 0.034 seconds

Hepatic Arterial Perfusion Scintigraphy with Tc-99m-Macroaggregated Albumin in Hepatocellular Carcinoma (Tc-99m-MAA를 이용한 간세포암의 경동맥 관류스캔)

  • Kim, Gang-Deuk;Sohn, Kwang-Joon;Min, Kyung-Yoon;Kwon, Young-Mi;Kim, Chang-Guhn;Noh, Byung-Suk;Won, Jong-Jin
    • The Korean Journal of Nuclear Medicine
    • /
    • v.28 no.3
    • /
    • pp.350-356
    • /
    • 1994
  • Purpose : Hepatic arterial perfusion scintigraphy with Tc-99m-macroggregated albumin (HAPS) study was carried out in 16 patients with hepatocellular carcinoma(HCC) and in six patients without liver tumor to evaluate HAPS findings of hepatocellular carcinoma and usefullness of HAPS. Materials and Methods : HAPS with planar and SPECT study were performed in 22 patients after conventional hepatic or celiac arteriography. For HAPS study, 4-5 mCi of MAA mixed with 2ml of saline was injected into proper hepatic artery or its distal branches at the rate of approximately 1ml/sec. We analysed 21 HCCs over 2cm in diameter(average diameter; 6.4cm) and 17 of 21 HCCs were over 4cm in diameter(Table 1). CT, sonography and angiography were performed within two week in all 16 patients and liver scan was performed in 12 patients. Results : Three different pattern of tumor perfusion were observed in 16 patients with HCC (Table 2). 1) diffuse increased perfusion in 16 of 21(76%)(Fig. 1) 2) increased peripheral perfusion in 4 of 21(19%) (Fig. 2) 3) diffuse decreased perfusion in 1 of 21 (5%) Arteriovenous shunt indicated by lung uptake of MAA were observed in 9 of 16(56%)(Fig. 4). In contrast, angiography demonstrates arteriovenous shunt in 2 of 16(13%). There was no accumulation of radioactivity on RBC-blood pool scan in all six patients with HCC examined (Fig. 1). Conclusion : HAPS is useful study in evaluation of perfusion pattern or vascularity of HCC and in detection of arteriovenous shunt.

  • PDF

Performance Analysis of Error Correcting Codes for HAPS (High Altitude Platform Station) (성층권 통신시스템(HAPS)을 위한 오류정정부호의 성능분석)

  • 백동철;구본준;안도섭;박광량
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.24 no.12A
    • /
    • pp.1966-1973
    • /
    • 1999
  • In this paper, we introduce the concept of a HAPS(High Altitude Platform Station) system which is expected to be a next generation communication system and suggest several error correcting codes to provide high quality services. Since a HAPS system encounters serious signal attenuation due to rain and scattering in the air, concatenated codes which have a high coding gain is considered to be a proper error correcting method. In this paper, we provide performance analyses result of two candidate coding schemes for a HAPS. The first one is a conventional concatenated coding scheme, and the second one is a iterative decoding method known as Turbo Codes.

  • PDF

Development of primary reference gas mixtures of 18 volatile organic compounds in hazardous air pollutants (5 nmol/mol level) and their analytical methods

  • Kang, Ji Hwan;Kim, Yong Doo;Lee, Jinhong;Lee, Sangil
    • Analytical Science and Technology
    • /
    • v.34 no.5
    • /
    • pp.202-211
    • /
    • 2021
  • Volatile organic compounds (VOCs) in hazardous air pollutants (HAPs) have been regulated by the Air Pollution Control Act (1978) and their atmospheric concentrations have been monitored in 39 monitor sites in Korea. However, measurement standards of volatile organic compounds (VOCs) in HAPs at ambient levels have not been established in Korea. Primary reference gas mixtures (measurement standards) at ambient levels are required for accurately monitoring atmospheric VOCs in HAPs and managing their emissions. In this study, primary reference gas mixtures (PRMs) at 5 nmol/mol were developed in order to establish primary national standards of VOCs in HAPs at ambient levels. Primary reference gas mixtures (PRMs) were prepared in pressurized aluminum cylinders with special internal surface treatment using gravimetric method. Analytical methods using gas chromatography-flame ionization detector (GC-FID) coupled with a cryogenic preconcentrator were also developed to verify the consistency of gravimetrically prepared HAP VOCs PRMs. Three different columns installed in the GC-FID were evaluated and compared for the retention times and separation of eighteen target components in a chromatogram. Results show that the HAP VOCs PRMs at 5 nmol/mol were consistent within a relative expanded uncertainty (k=2) of less than 3 % except acrylonitrile (less than 6 %) and the 18 VOCs were stable for 1 year within their associated uncertainties.

Use of unmanned aerial systems for communication and air mobility in Arctic region

  • Gennady V., Chechin;Valentin E., Kolesnichenko;Anton I., Selin
    • Advances in aircraft and spacecraft science
    • /
    • v.9 no.6
    • /
    • pp.525-536
    • /
    • 2022
  • The current state of telecommunications infrastructure in the Arctic does not allow providing a wide range of required services for people, businesses and other categories, which necessitates the use of non-traditional approaches to its organization. The paper proposes an innovative approach to building a combined communication network based on tethered high-altitude platform station (HAPS) located at an altitude of 1-7 km and connected via radio channels with terrestrial and satellite communication networks. Network configuration and composition of telecommunication equipment placed on HAPS and located on the terrestrial and satellite segment of the network was justified. The availability of modern equipment and the distributed structure of such an integrated network will allow, unlike existing networks (Iridium, Gonets, etc.), to organize personal mobile communications, data transmission and broadband Internet up to 100 Mbps access for mobile and fixed subscribers, rapid transmission of information from Internet of Things (IoT) sensors and unmanned aerial vehicles (UAV). A substantiation of the possibility of achieving high network capacity in various paths is presented: inter-platform radio links, subscriber radio links, HAPS feeder lines - terrestrial network gateway, HAPS radio links - satellite retransmitter (SR), etc. The economic efficiency of the proposed solution is assessed.

HAPS 시스템 구현을 위한 최근의 연구동향

  • Gang, Yeong-Heung
    • Information and Communications Magazine
    • /
    • v.25 no.9
    • /
    • pp.64-70
    • /
    • 2008
  • 본고에서는 20km-50km 성층권상공에 위치하는 HAPS(High Altitude Platform Station) 구현을 위한 최근의 연구동향에 대해 알아본다. 기존의 지상 및 위성통신시스템에 비해 HAPS만의 고유의 특징을 살려 3G 이상의 광대역 이동 통신서비스 및 재난재해 응용 등 일본, 미국, 유럽에서 차세대 HAPS에 대한 연구를 활발히 진행하고 있는 시점에서 이들의 연구동향을 분석하여 소개함으로 서, 향후 국내에서도 국가적인 차원의 HAPS 연구개발이 활발히 이루어질 수 있는 계기가 마련될 수 있으리라 기대한다.

Analytical Methods for Spatial Distribution of Hazardous Air Pollutants (HAPs)

  • Amagai, Takashi
    • Proceedings of the Korea Air Pollution Research Association Conference
    • /
    • 2010.04a
    • /
    • pp.41-44
    • /
    • 2010
  • Hazardous air pollutants such as benzo[a]pyrene (BaP), benzene, formaldehyde have been concerned about the adverse health effect of long-term exposure. Contour map is useful for finding high-concentration region, emission source, and distributions of HAPs in the ambient air. To make a contour map, we have developed simple analytical method for selected HAPs; polycyclic aromatic hydrocarbons such as BaP, benzene and its derivatives such as toluene and xylene, and aldehydes and ketones. We have applied these methods to investigate air pollution by HAPs in some cities in Japan. The results show that these methods reveal actual emission sources if the PRTR emission report was not submitted.

  • PDF

An Economic Feasibility Analysis of the HAPS Services in Korea

  • Ahn, Jae-Kyung;Kim, Jong-Hwa;Lee, Deok-Joo;Ahn, Do-Seob;Ku, Bon-Jun
    • Satellite Communications and Space Industry
    • /
    • v.13 no.1 s.28
    • /
    • pp.118-124
    • /
    • 2006
  • HAPS(High Altitude Platform Station) which is defined as a station located on an object at an altitude of 20 to 50 km and at a specified, nominal, fixed point relative to the earth is promising technology capable of providing broadband multimedia services. In this study, economical aspects of HAPS service are analyzed by estimating the revenue and costs incurred by the service. To evaluate the profitability of HAPS service, the number of subscribers is estimated and then the net present value (NPV), payback period, and the rate of return on investment (ROI) are calculated under various scenarios

  • PDF

Analysis of the International Standardization and Technology on HAPS (HAPS 국제표준화 및 국외 기술 동향 분석)

  • Ku, B.J.;Ahn, D.S.
    • Electronics and Telecommunications Trends
    • /
    • v.15 no.5 s.65
    • /
    • pp.49-59
    • /
    • 2000
  • WRC-2000 회의를 계기로 성층권 통신시스템용 주파수가 새롭게 분배됨에 따라 정보통신 인프라가 취약한 후진국 및 개도국뿐만 아니라 여러 선진국들을 중심으로 성층권 비행선을 이용한 통신 및 무선응용 서비스의 활용에 대해서 관심이 점점 높아지고 있다. 본 논문에서는 성층권 통신시스템의 개요를 소개하고 WRC-2000 회의의 HAPS(High Altitude Platform Station) 관련 주요 의제 및 진행 경과와 결과를 중심으로 국제 표준화 동향을 알아보고자 한다. 그리고 현재 미국, 일본 및 유럽 등 몇몇 기술 선진국을 중심으로 진행되고 있는 성층권 통신시스템 개발과 관련하여 기술 개발 동향에 대해서 살펴보고 성층권 통신시스템(HAPS)의 기대효과 및 향후 전망에 대해서 논의하고자 한다.

Influence of HAPS and GEO Satellite under SANDU Layering and Gas Attenuations

  • Harb, Kamal
    • International Journal of Computer Science & Network Security
    • /
    • v.21 no.12
    • /
    • pp.93-100
    • /
    • 2021
  • Satellite communication for high altitude platform stations (HAPS) and geostationary orbit (GEO) systems suffers from sand and dust (SANDU) storms in desert and arid regions. The focus of this paper is to propose common relations between HAPS and GEO for the atmospheric impairments affecting the satellite communication networks operating above Ku-band crossing the propagation path. A double phase three-dimensional relationship for HAPS and GEO systems is then presented. The comparison model present the analysis of atmospheric attenuation with specific focus on sand and dust based on particular size, visibility, adding gas effects for different frequency, and propagation angle to provide systems' operations with a predicted vision of satellite parameters' values. Thus, the proposed system provides wide range of selecting applicable parameters, under different weather conditions, in order to achieve better SNR for satellite communication.